Fluid mounts for attachment between a supporting member and a supported member are taught in U.S. Pat. No. 4,811,919 to Jones, the disclosure of which is hereby incorporated by reference. In Jones '919, the fluid inertia within the mount can be tuned to provide amplified counter inertial forces that coincide with an operating frequency of a vibrating aircraft engine. However, in order to produce these fluid forces the beam 11 of mount must be loaded in a particular direction such that fluid is transferred from chamber 40 to chamber 41 through tube 45. This can only be accomplished by translation of stub shaft 10 toward frame 20 in a vertical direction thus urging fluid to flow through tube 45. Torsional or cocking rotation of the Jones '919 mount will not set the fluid in motion through tube 45 and hence, no damping or inertial effects will be obtained.
U.S. Pat. No. 2,705,118 to Beck, the disclosure of which is also hereby incorporated by reference, discloses a mounting arrangement that incorporates fluid damping in either a torsional mode or a vertical mode, depending on the orientation of the mounts, but not in both orientations at once. Beck '118 describes a fluid torque restraint in FIG. 4, wherein mounts are located on opposite sides of the torque axis of gear box 17. When torque is applied, fluid 6 in chambers 5 and conduits 9 are placed in compression. This provides a high degree of torque restraint, i.e., a high torsional stiffness. However, when the gear box 17 is subjected to vertical translational loads, fluid is free to flow through conduit 9 and valve 10, thus providing damping and a soft translational stiffness. In the FIG. 3 embodiment, contrarily, the mount arrangement imparts a high vertical stiffness yet provides a low rotational or torsional stiffness. When the engine 11 is subjected to rotational or torsional loading, fluid is free to flow through conduit 9 and valves 10, thus providing fluid damping and a low torsional stiffness. However, the Beck '118 device cannot provide damping in both the vertical and rotational modes simultaneously. Further, the mounts in Beck must be spaced on opposite sides of the torque axis of the supported body.
U.S. Pat. No. 4,881,712 to Lun discloses an engine mount assembly 16 which displaces fluid from engine mounts 20 to 22 through track 23 to provide damping when subjected to torsional loading. However, mount 16 cannot provide damping when the loading is vertical on both mounts 20 and 22 because no fluid will flow through track 23.
U.S. Pat. No. 4,784,378 to Ford discloses a mounting assembly for supporting an engine 10 including mounts 20 and 30 interconnected by conduits 41 and 42 and vacuum accumulator 70. Although Ford can provide some vertical-mode, as well as torsional-mode, damping, the mounts must be spaced on opposite sides of a torque axis. Further the exposed conduits are subject to failure due to corrosion and strikes. Furthermore, several mounts are required to provide torsional support.